Continuously variable inductance



Oct. 26, 1948. c. E. PAYNE ZAEZAQ CONTI'NUOUSLY VARIABLE INDUCTANCE Filed NOV. 3, 1944 A1" 'IORNEY Patented Oct. 26, 1948 CONTINUOUSLY VARIABLE INDUCTANCE Charles Edward Payne, London, England, as-

signor to The Hartford National Bank and Trust Company, Hartford, Conn., as trustee Application November 3, 1944, Serial No. 561,816

In Great Britain June 22, 1943 Section 1, Public Law 690, August 8, 1946 Patent expires June 22, 1963 This invention relates to continuously variable inductances, and like electrical apparatus in which electrical contact has to be produced between a contact member and any selected part of the length of a conductor forming the inductance or the like. The conductor is usually in the form of a wire wound as an open helix and the contact member is caused to move along the helix.

According to the present invention in such apparatus the contact member is in the form of a roller which in its movement lengthwise of the conductor is constrained to rotate at a speed different from that corresponding to a simple rolling movement on the conductor. In this way a continuously wiped contact with a continuous presentation of a fresh working surface on the contact member is ensured during the adjustment of the inductance or the like.

Preferably the contact roller is driven from the means causing its movement relative to the in-y ductance. Thus for example the helical conductor of the inductance may be caused to rotate about the axis of the helix and the IContact roller which has a V groove engaging the conductor, may be slidable along a squared shaft mounted parallel to the axis of the |helix and driven from the helix by suitable gearing or by a belt or friction drive.

In order that the invention may be more read. ily understood and carried into effect it will now be described with reference to the accompanying drawing in which:

Fig. 1 is an end view of a variable inductance unit in accordance with the invention illustrating one form of driving arrangement for the roller;

Fig. 2 is a longitudinal section of the coil shown in Fig. l illustrating the construction for assuring positive and continuous contact between the coil and the rolling contact; and

Fig. 3 illustrates an alternative construction of the driving arrangement for the roller.

Referring rst to Fig. 1, the apparatus comprises a rigid framework consisting of two end plates I secured in xed relationshipby connecting rods 2.

Journalled in bearings in the end plates I is a shaft 3 carrying a cylindrical former or drum 4 which is coaxial with the shaft. Wound on the drum 4 in the form of an open helix is a wire 5 the ends of which are connected in known manner to contact wheels 1 (only one of which is visible in Fig. l). These wheels rotate with the drum 4 and the shaft 3 but are insulated from the latter. Contact to the wheels 'l is established by springs 6 secured on terminal 4 Claims. (C1. 171-242) 2 posts 8 to which connecting leads 9 are attached.

Contact with any desiredpoint of the helix 5 is established by a grooved roller I0 which slides on and rotates with a squared shaft II which extends parallel to the shaft 3. The shaft II is carried in insulating bearings in a pair of levers I2 which are xed on a pivot shaft I3 extending between and carried by bearings in the end plates I. The electrical connection to the roller I0 is obtained by means of -contact wheels I6, springs I5, terminal posts I1 and leads I8, corresponding to the Wheels l, springs G, terminal posts 8 and leads 9 associated with the drum 4.

To maintain suitable contact pressure between the roller I and the Wire helix 5, the levers I2 are loaded by springs I4 .so that eccentricities such as arise in manufacturing practice are automatically compensated.

During rotation oi the drum 4, the contact roller IIJ is constrained by the engagement of its grooved periphery with the wire 5 to slide lengthwise of the shaft II. According to the present invention, the roller I8 is also constrained to rotate during rotation of the drum 4 at a speed different from that corresponding to a simple rolling movement along the wire 5. In Fig. l, a pulley I9 on the shaft 3 is coupled with a pulley 2D on the shaft I I by means of a belt 2|, the dimensions of the pulleys being so chosen in the case of Fig. 1 in relation to the diameters of the drum 4 and roller ID as to cause the roller to have a higher peripheral speed than the drum. In this way a wiping contact is obtained with a constantly fresh surface of the roller ID coming into operation, thereby enabling a satisfactory electrical Contact to be produced with a minimum of wear and a minimal contact pressure between roller IU and wire 5. It will -be apparent that precisely the same effect can be achieved by driving the roller I0 at a higher peripheral speed than the drum 4.

As shown` both the shaft 3 and the shaft II extend through and beyond the right hand end plate I. Consequently, owing to the different diameters of the drum 4 and the roller I 0, a rapid adjustment can be obtained by rotating the shaft 3, and fine adjustment by rotating the shaft I I.

In the modification shown in Fig. 3 those parts which correspond with those already described with reference to Fig. 1 are indicated by the same reference numerals as in Fig. l and will not be further described. The construction of Fig. 2 differs from that of Fig. 1 principally in that a gear train is employed for coupling the drum 4 with the roller I0. The gear wheel 23 fast on the shaft 3 drives the wheel 28 fast on the shaft I I by way of the intermediate wheels 24, 25, the transmission ratio for the gear train shown being such that the roller I has a higher peripheral speed than the drum 4. The shaft I I in Fig. 2 does not extend through the end plate I but fine adjustment is performed by means of the shaft 21 on Iwhich the gear wheel 25 is secured. This shaft 21 also serves as pivot for the levers I2,A so that pivotal novement of these levers does not affect the meshing of the gears.

I claim:

1. Electrical apparatus comprising a continuous conductor mounted on a support, means rotatably mounting said support, a contact mem- -ber in the form of a roller, means for causing said contact roller to traverse the length of said conductor by rotation of said support to enable the point of contact to be at 4any position within the length traversed by said contact roller, means for maintaining a desired contact pres- Vsure between said conductor and said roller, and

driving means mechanically linking said roller to said -rotatable support for constraining said roller to rotate at a speed substantially different from that corresponding to -a simple rolling movement on said conductor when said rotatable support is rotated whereby an effective wiping contact between said roller and said continuous conductor is obtained during operation of the electrical apparatus.

2. Electrical apparatus comprising a continuous conductor disposed in the form of an open wound helix, means for supporting said open wound helix, means rotatably mounting said supporting means, a contact roller engaging said conductor means for causing relative movement between said helix and said roller so that said roller traverses the length of said helix upon rotation of said supporting means, means for maintaining a desired contact pressure between said conductor and said roller, and driving means mechanically linking said roller to said rotatable supporting means for constraining said roller to rotate at a speed substantially diierent from that corresponding to a simple rolling movementl on said conductor when said rotatably supporting means is rotated whereby an effective wiping contact between said roller and said continuous conductor.- is obtained during operation of the electrical apparatus.

3. Electrical apparatus comprising a continuous wire conductor wound in the form of an open helix on a cylindrical support mounted for rotation about its axis, a contact roller with a grooved periphery engaging said wire and mounted for rotation with and .translation along a shaft extending parallel to the axis of said cylindrical support, self-adjusting resilient means for imparting an approximately constant contact pressure between said conductor and said roller, and driving means mechanically linking said roller to said cylindrical support for constraining said roller to rotate at a speed substantially different from that corresponding to a simple rolling movement on said wire when said cylindrical support is rotated whereby an effective wiping contact between said roller and said wire is obtained during operation of the electrical apparatus.

4. Electrical apparatus comprising a continuous wire conductor wound in the form of an open helix on a cylindrical support mounted for rotation about its axis, a contact roller with a grooved periphery engaging said wire and mounted for rotation with and translation along a shaft extending parallel to the axis of said cylindrical support, spring-controlled means for maintain` ing a contact pressure between said conductor and said roller, a driving connection between said cylinder and said shaft for constraining said roller to rotate at a linear peripheral speed substantially different from the linear peripheral speed of said cylinder, and means for imparting rotation to one of said rotatable elements whereby an eiective wiping contact between said roller and said wire is obtained dulring operation of the electrical apparatus.

CHARLES EDWARD'PAYNE.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS 

